All real definitions of ELF_HWCAP are now identical, and the stub
definitions are 0.  Provide a weak stub as a fallback definition.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/elfload.c | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index cd83307750..8036f902cc 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -38,7 +38,6 @@
 #ifdef _ARCH_PPC64
 #undef ARCH_DLINFO
 #undef ELF_PLATFORM
-#undef ELF_HWCAP
 #undef ELF_HWCAP2
 #undef ELF_CLASS
 #undef ELF_DATA
@@ -158,8 +157,6 @@ typedef abi_int         target_pid_t;
 
 #ifdef TARGET_I386
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 #ifdef TARGET_X86_64
 #define ELF_CLASS      ELFCLASS64
 #define ELF_ARCH       EM_X86_64
@@ -459,7 +456,6 @@ static bool init_guest_commpage(void)
     return true;
 }
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
 #define ELF_HWCAP2 get_elf_hwcap2(thread_cpu)
 
 #define ELF_PLATFORM get_elf_platform()
@@ -549,7 +545,6 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
 #define USE_ELF_CORE_DUMP
 #define ELF_EXEC_PAGESIZE       4096
 
-#define ELF_HWCAP   get_elf_hwcap(thread_cpu)
 #define ELF_HWCAP2  get_elf_hwcap2(thread_cpu)
 
 #if TARGET_BIG_ENDIAN
@@ -575,8 +570,6 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
 # define ELF_ARCH   EM_SPARCV9
 #endif
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 static inline void init_thread(struct target_pt_regs *regs,
                                struct image_info *infop)
 {
@@ -608,7 +601,6 @@ static inline void init_thread(struct target_pt_regs *regs,
 
 #define ELF_ARCH        EM_PPC
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
 #define ELF_HWCAP2 get_elf_hwcap2(thread_cpu)
 
 /*
@@ -735,8 +727,6 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
 #define USE_ELF_CORE_DUMP
 #define ELF_EXEC_PAGESIZE        4096
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 #define ELF_PLATFORM "loongarch"
 
 #endif /* TARGET_LOONGARCH64 */
@@ -844,8 +834,6 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUMIPSState *e
 #define USE_ELF_CORE_DUMP
 #define ELF_EXEC_PAGESIZE        4096
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 #endif /* TARGET_MIPS */
 
 #ifdef TARGET_MICROBLAZE
@@ -919,7 +907,7 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
     (*regs)[32] = tswapreg(env->pc);
     (*regs)[33] = tswapreg(cpu_get_sr(env));
 }
-#define ELF_HWCAP 0
+
 #define ELF_PLATFORM NULL
 
 #endif /* TARGET_OPENRISC */
@@ -973,8 +961,6 @@ static inline void elf_core_copy_regs(target_elf_gregset_t *regs,
 #define USE_ELF_CORE_DUMP
 #define ELF_EXEC_PAGESIZE        4096
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 #endif
 
 #ifdef TARGET_M68K
@@ -1049,8 +1035,6 @@ static inline void init_thread(struct target_pt_regs *regs,
 #define ELF_DATA	ELFDATA2MSB
 #define ELF_ARCH	EM_S390
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
 {
     regs->psw.addr = infop->entry;
@@ -1109,8 +1093,6 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
 #define VDSO_HEADER "vdso-64.c.inc"
 #endif
 
-#define ELF_HWCAP get_elf_hwcap(thread_cpu)
-
 static inline void init_thread(struct target_pt_regs *regs,
                                struct image_info *infop)
 {
@@ -1278,10 +1260,6 @@ static inline void init_thread(struct target_pt_regs *regs,
 #define elf_check_abi(x) (1)
 #endif
 
-#ifndef ELF_HWCAP
-#define ELF_HWCAP 0
-#endif
-
 #ifndef STACK_GROWS_DOWN
 #define STACK_GROWS_DOWN 1
 #endif
@@ -1301,6 +1279,14 @@ static inline void init_thread(struct target_pt_regs *regs,
 #define EXSTACK_DEFAULT false
 #endif
 
+/*
+ * Provide fallback definitions that the target may omit.
+ */
+abi_ulong __attribute__((weak)) get_elf_hwcap(CPUState *cs)
+{
+    return 0;
+}
+
 #include "elf.h"
 
 /* We must delay the following stanzas until after "elf.h". */
@@ -1878,7 +1864,7 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
     NEW_AUX_ENT(AT_EUID, (abi_ulong) geteuid());
     NEW_AUX_ENT(AT_GID, (abi_ulong) getgid());
     NEW_AUX_ENT(AT_EGID, (abi_ulong) getegid());
-    NEW_AUX_ENT(AT_HWCAP, (abi_ulong) ELF_HWCAP);
+    NEW_AUX_ENT(AT_HWCAP, get_elf_hwcap(thread_cpu));
     NEW_AUX_ENT(AT_CLKTCK, (abi_ulong) sysconf(_SC_CLK_TCK));
     NEW_AUX_ENT(AT_RANDOM, (abi_ulong) u_rand_bytes);
     NEW_AUX_ENT(AT_SECURE, (abi_ulong) qemu_getauxval(AT_SECURE));
-- 
2.43.0

On Wed, 30 Jul 2025 at 01:49, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> All real definitions of ELF_HWCAP are now identical, and the stub
> definitions are 0.  Provide a weak stub as a fallback definition.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  linux-user/elfload.c | 34 ++++++++++------------------------
>  1 file changed, 10 insertions(+), 24 deletions(-)

> +/*
> + * Provide fallback definitions that the target may omit.
> + */
> +abi_ulong __attribute__((weak)) get_elf_hwcap(CPUState *cs)
> +{
> +    return 0;
> +}

We make very little use of the weak attribute elsewhere in the
codebase, so I'm not super enthusiastic about adding it, but I
guess for linux-user we don't have the portability problems
that it can create...

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM